1304-ETN9 bearing: complete specifications & equivalents
The 1304-ETN9 is a ISO 15 radial bearing sized 20 x 52 x 15 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 52 mm |
| Width B | 15 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 14.3 kN |
| Basic static load rating C0 | 4 kN |
| Fatigue load limit Pu | 0.21 kN |
| Reference speed (thermal) | 26000 rpm |
| Limiting speed (mechanical) | 18000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 160 g |
| Manufacturer designation | 1304 ETN9 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 1300-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.591 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 16 mm |
| Smallest bore in 1300-series | 5 mm |
| Largest outer diameter in 1300-series | 320 mm |
| Width range across 1300-series | 6–74 mm |
| Bore position in 1300-series (smallest first) | 6 of 29 |
| Bore above smallest 1300-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 1304 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×52×15 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 1304-ETN9 model number is decoded
The 13xx series is the medium/normal-section self-aligning ball bearing (ISO dimension series 03). the last two digits encode the bore: 1304 carries code 04 = 20 mm (code × 5). Envelope 20×52×15 mm (0.787×2.047×0.591 in) with a 16.0 mm radial section height, C 14.3 kN, C0 4 kN and Pu 0.21 kN. The open 1304 ETN9 carries no shields or seals and relies on application lubrication and external sealing. The ETN9 suffix identifies the glass-fibre-reinforced polyamide 66 cage execution. The bore is cylindrical (straight), for a press-fit on a 20 mm shaft. Reference (thermal) speed 26000 r/min, limiting speed 18000 r/min, catalogue mass 160 g.
Typical equipment & failure modes
Common applications
- conveyor idler rollers
- agricultural machinery shafts
- textile spindles and looms
- fan and blower shafts
Known failure patterns
- contamination wear when the open arrangement is used without adequate external sealing
- lubricant starvation where no regreasing interval is maintained
- brinelling from static overload or hammer blows during mounting
- false brinelling from vibration while the shaft stands idle
Selection pitfalls — read before you substitute
- The spherical outer raceway lets 1304-ETN9 tolerate shaft deflection, but it does not increase thrust capacity — combined loads still need an angular-contact or deep-groove bearing.
- The fatigue load limit is 0.21 kN; it feeds the equivalent-mean-load check, not the basic life calculation — do not substitute one for the other.
- The ETN9 suffix on 1304-ETN9 denotes a glass-fibre-reinforced polyamide 66 cage: quiet and light at the 18000 r/min limiting speed, but it softens above roughly 120 °C — check the oil temperature in hot drives.
- Fillet radii must clear the 1304-ETN9 chamfer so the 15 mm-wide ring seats square; an oversized shaft radius creates point contact on the ring face.
- Self-aligning ball bearings tolerate up to roughly 2–3° of static misalignment, but the sealed 1304-ETN9 (2RS1) allows less — the lip seal binds before the spherical raceway does.
- Assign interference to the rotating ring: on a 20 mm rotating shaft use a k5 seat with an H7 housing; reverse the logic if the outer ring rotates.
Frequently asked questions
What are the dimensions of 1304-ETN9?
SKF 1304 ETN9 measures 20 mm bore × 52 mm OD × 15 mm width (0.787 × 2.047 × 0.591 in), mass about 160 g. It is open, with no shields or seals.
How does the bore code in 1304 work?
The final two digits of 1304 are bore code 04, multiplied by 5 to give 20 mm.
How heavy is 1304-ETN9?
Catalogue mass is 160 g for 1304 ETN9; seal and cage executions of the same envelope differ by a few grams.
What load can 1304-ETN9 take?
Catalogue values for 1304 ETN9: dynamic C 14.3 kN, static C0 4 kN, fatigue limit Pu 0.21 kN. Use C in life calculation and C0 for static checks at 20 mm bore.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.